Swift 3 - 自定义淡入淡出

Question

我正在尝试从一个ViewController到另一个ViewController进行自定义转换，但由于某种原因我似乎无法正确使用它。 我想要＆＃34; fromView＆＃34;淡出和＆＃34; ToView＆＃34;淡出印度，我没有＆＃39; 我认为这会很难 - 但显然这并不容易。

现在我使用NSObject声明转换函数，并从＆＃34; prepare（for segue＆＃34;在我的ViewController中）调用它。但是出了点问题。

我的自定义转换：

class FadeAnimator: NSObject, UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate {

let duration = 1


func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return self
}

func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return self
}

func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
    return TimeInterval(duration)
}

func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {

    guard let fromView = transitionContext.view(forKey: UITransitionContextViewKey.from) else {
        return
    }

    guard let toView = transitionContext.view(forKey: UITransitionContextViewKey.to) else {
    return
    }


    let container = transitionContext.containerView


    container.addSubview(fromView)
    container.addSubview(toView)

    UIView.animate(withDuration: TimeInterval(duration), delay: 0.0, usingSpringWithDamping: 0.8, initialSpringVelocity: 0.8, options: [], animations: {

        UIView.animate(withDuration: 2, animations: {
            fromView.alpha = 0
        }, completion: { (true) in
            toView.alpha = 1
        })


    }) { (succes) in
        transitionContext.completeTransition(succes)
    } 
}

我的ViewController.swift：

  let fadeAnimater = FadeAnimator()



    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let destination = segue.destination

    destination.transitioningDelegate = FadeAnimator() as! UIViewControllerTransitioningDelegate
}